In circuits that convey fluids under pressure and that make use of quick connectors, it is desirable, and often required, to make use of means that lock a connection in positive manner. A badly-made connection is firstly a source of leakage, and secondly runs the risk of decoupling, where the least severe consequence is a breakdown of the machine including said pressurized fluid circuits, and if the machine is a motor vehicle, a more severe consequence could be to lead to an accident (no pressure in the hydraulic brake circuit, fuel leaking into the engine compartment possibly leading to a fire, . . . ).
Numerous devices exist for locking the male element in the female element of a quick connector. Substantially all of them operate on the same principle and implement identical general means consisting in a keying member which is interposed between a radial surface of the endpiece (a groove or a collar) and a radial surface of the female element (likewise a groove or a collar). The keying member may be inserted manually or it may be held in its locking position by a resilient return member, the keying member being suitable, while the endpiece is being inserted, for being put into a retracted position against the force of the return member (either by being displaced or by being deformed).
In a particularly simple embodiment of such a device as described in document FR 2 705 430, the latch is constituted by a ring mounted to slide radially in a housing formed in the female part of the connector between a rest and locking first position in which it is off-center relative to the axis of the bore of the female part, and a retracted second position in which it lies substantially on the axis of said bore.
A resilient member constituted by two tongues made integrally with the ring is interposed between the ring and the female part, and urges the ring towards its first position after the collar has passed through.
It is found that that mode of locking does not provide sufficient guarantee that the male part has been properly engaged in the female part. The male part can be engaged sufficiently for the collar to force the ring to move against the return tongues, but not far enough for the collar to clear the ring, thereby preventing the ring from taking up its locking position behind the collar under drive from the elastic tongues. This situation is not blatantly visible to the operator, who might believe that the connection has been made properly.
Documents EP 0 505 930, EP 0 846 907, FR 2 705 432, and U.S. Pat. No. 6,145,886 disclose connectors fitted with locking indicators that indicate that the connector has been locked properly, the locking indicator being disposed downstream from the locking member so as to be driven by the collar after it has gone past the locking member. In the connectors illustrated in those documents, the female part has special openings to enable co-operation between the locking indicator and the collar of the male part while it is being inserted, thereby weakening the female part and making it more complicated to manufacture.
In document EP 0 992 729, the locking indicator is likewise disposed in an axially off-center position relative to the locking member, but upstream from the locking member at the end of the female part. The locking indicator is driven not by the collar of the male part, but by an accessory entrained by the male part on being inserted in the female part, thereby making that type of connector more complex.